EDN3

Variants (also known as mutations) in the EDN3 gene have been found to cause Hirschsprung disease, a disorder that causes severe constipation or blockage of the intestine. Although Hirschsprung disease is a feature of another disorder called Waardenburg syndrome type IV (described below), EDN3 gene variants can also cause Hirschsprung disease in people without Waardenburg syndrome. These variants change one DNA building block (nucleotide) or insert an additional nucleotide in the gene. Changes in the EDN3 gene disrupt the normal function of endothelin 3, preventing it from playing its usual role in the development of enteric nerves. As a result, these cells do not form normally during embryonic development. A lack of enteric nerves prevents stool from being moved through the intestine normally, leading to severe constipation or intestinal blockage.

Variants in the EDN3 gene have been identified in people with Waardenburg syndrome type IV (also known as Waardenburg-Hirschsprung disease or Waardenburg-Shah syndrome). This type of Waardenburg syndrome is characterized by changes in skin, hair, and eye coloring; hearing loss; and Hirschsprung disease (described above). EDN3 gene variants change single nucleotides in the gene, preventing the production of a functional endothelin 3 protein. Because active endothelin 3 is necessary for the formation of enteric nerves and melanocytes, these cell types do not form normally during embryonic development. Missing enteric nerves in certain parts of the intestine cause the signs and symptoms of Hirschsprung disease. A lack of melanocytes affects the coloring of skin, hair, and eyes and causes the hearing loss characteristic of Waardenburg syndrome.